In methane partial conversion processes (e.g., oxidative coupling of methane (OCM) process, single-step methane to olefins conversion process, etc.), natural gas comprising primarily methane along with other hydrocarbons and inerts (such as nitrogen) is converted to chemical intermediates (e.g., olefins, such as ethylene and propylene; alkanes, such as ethane and propane). Depending on where the natural gas is sourced, the inerts (e.g., nitrogen) content in the natural gas can be relatively high (2-7 mol %). Such inerts content poses a challenge in terms of processing in a recycle process, as inerts tend to build up in recycle streams. Further, such inerts content can lead to large recycle rates in the process, as well as potentially reduced reaction efficiency due to dilution of the reactants, thus leading to larger sizes of major equipment such as reactors, compressors and columns.
A conventional method of dealing with the issue of high inerts content is to increase the purge rate from the process so as to reduce the concentration of inerts (e.g., nitrogen) in recycle loops. However, unconverted methane is also lost from the process in this purge, which means that this approach requires an increased make-up feed rate and results in a lower carbon efficiency of the overall conversion process. While the purge gas can be burned to generate power, this approach would require investment in the form of power plant equipment. Thus, there is an ongoing need for the development of methane partial conversion processes that minimize inerts content in recycle loops via process modifications which do not result in large capital investments in the compression and separation equipment.